The present invention relates generally to methods and apparatus for providing high speed electronic assembly, and more particularly to improved methods and apparatus for manufacturing printed circuit boards.
A typical electronic circuit board manufacturing process involves a number of operations, each of which is performed by an independent machine. These operations typically include stenciling a pattern of solder onto the pads of an incoming circuit board, placing electrical components on the pads of the board and heating the board to establish the integrity of the contact between the solder, the board and the components. Depending on the particular application, the manufacturing operation may also include other operations, such as dispensing encapsulents or adhesives, curing the encapsulents or adhesives, and optically inspecting completed or partially completed boards. The manufacturing operations are typically done in a serial production line in which the machines for each process are coupled together using conveyors for transporting partially completed boards from one machine to the next.
FIG. 1 shows a block diagram of a typical electronic circuit board production line 10. The circuit board production line includes a printer 12, a component placement machine 14, an automated optical inspection system 16, a dispenser 18, an oven 20, and an automated board handling system 22 between each of the machines. The printer 12 is used to stencil solder paste onto boards. The component placement machine 14 is used to place electrical components on the circuit boards. The dispenser 18 may be used to perform a number of functions such as the deposition of underfill material around and under components placed on the boards. The optical inspection system 16 is used to inspect the boards in the line. Additional inspection systems may be added to the line, or incorporated in the machines of the line, to ensure that production quality standards are met. The oven 20 is used to reflow the solder paste printed by the printer. A separate oven may be used to cure adhesives and encapsulents deposited by the dispenser 18. For some board production applications, additional machines may be added to the production line and/or some of the machines shown in FIG. 1 may not be included.
Because of the cost and availability of manufacturing floor space, and because of ever tightening quality requirements there is a need for higher speed more reliable circuit board manufacturing production lines. To maintain high speed output from production lines, it is desirable to have minimum downtime of the lines. Accordingly, it is typically required that machines used in circuit board production lines have high reliability requirements and low mean time to repair requirements. These requirements often lead to the machines becoming more expensive than desirable.
Embodiments of the present invention provide improved processes and apparatus for producing electronic circuit boards and other substrates.
A first aspect of the present invention is directed to a production system for producing completed substrates from raw substrates. The production system includes a first production line having an input to receive raw substrates, an output that provides completed substrates and a plurality of machines, coupled in series and arranged substantially along a first axis. The production system further includes a second production line having an input to receive raw substrates and an output that provides completed substrates. The second production line includes a plurality of machines, coupled in series and arranged along a second axis that is substantially parallel to the first axis. In addition, the production system includes a set of spare machines disposed along a third axis that is substantially parallel to the first axis and the second axis, the third axis being disposed between the first axis and the second axis. Each machine of the spare machines is similar to, and may function as a replacement for, at least one of the machines in the first production line and is similar to, and may function as a replacement for, one of the machines of the second production line.
The completed substrates may be circuit boards having components disposed thereon. The set of spare machines may be configured as a third production line having an input to receive raw substrates and an output that provides completed substrates. The first production line may include a first printer, a second printer and a transfer station. At least the first production line may include a first dispensing machine having an input, an output, and a shuttle conveyor system, wherein the shuttle conveyor system includes movable conveyor segments that allow a second circuit board to be moved from the input of the first dispensing machine to the output of the first dispensing machine while material is dispensed on a first circuit board in the first dispensing machine. Further, at least the first production system may include a second dispensing machine disposed after the first dispensing machine in the first production system, the second dispensing machine having an input, an output, and a shuttle conveyor system, wherein the shuttle conveyor system includes movable segments that allow the first circuit board to be moved from the input of the second dispensing machine to the output of the second dispensing machine while material is dispensed on the second circuit board in the second dispensing machine.
In another aspect of the present invention, a method of manufacturing completed substrates from raw substrates in a production system having a first production line and a second production line is provided. The method includes providing a spare set of machines disposed on a production floor between the first production line and the second production line, detecting a failed machine in one of the first production line and the second production line, and replacing the failed machine with a machine from the spare set of machines.
The method may further include steps of arranging the spare set of machines as a production line and producing completed substrates using the first production line, the second production line and the third production line. At least the first production line may include a dispensing machine, and the method may further includes steps of loading a first substrate into the dispensing machine, moving the first substrate to a dispensing position in the dispensing machine, dispensing material onto the first substrate, loading a second substrate into the dispensing machine and unloading the second substrate from the dispensing machine while the first substrate is at the dispensing position.
In yet another aspect, a printing system for use in a production line that produces completed substrates is provided. The printing system includes a first printer that prints material onto a substrate, the first printer having an input to receive raw circuit boards and an output that provides circuit boards having material printed thereon, a second printer that prints material onto a substrate, the second printer having an input to receive raw circuit boards and an output that provides circuit boards having material printed thereon, and a transfer station having a first input, a second input and an output, wherein the first input is coupled to the output of the first printer to receive circuit boards, the second input is coupled to the output of the second printer to receive circuit boards, and the output provides circuit boards. The transfer station may be configured to alternately provide at its output circuit boards from the first printer and circuit boards from the second printer.
Still another aspect of the present invention provides a dispensing system for dispensing material onto substrates. The dispensing system includes an input to receive substrates, an output that provides substrates, a dispensing head that dispenses material onto substrates, and means for moving a second substrate from the input to the output while the first substrate is disposed beneath the dispensing head and material is being dispensed on the first substrate.
The means for moving may include a shuttle conveyor system. The shuttle conveyor system may include an input conveyor segment coupled to the input and configured to convey substrates in a first direction along a first axis, an output conveyor segment coupled to the output and configured to convey substrates in the first direction along the first axis, a center conveyor segment having a front segment and a back segment, each of the front segment and the back segment being configured to convey substrates in the first direction along the first axis, and each of the front segment and the back segment being movable along a second axis, normal to the first axis, to align one of the front segment and the back segment with the input conveyor segment and the output conveyor segment. The dispensing system may further include a front dispensing location and a back dispensing location, wherein the front segment is movable between a center location aligned with the input conveyor segment and the front dispensing location, and wherein the back segment is movable between the center location and the back dispensing location. In addition, the dispensing system may further include a gantry system coupled to the dispensing head that moves the dispensing head over substrates disposed on the front dispensing location and over substrates disposed on the back dispensing location. dr
For a better understanding of the present invention, reference is made to the drawings which are incorporated herein by reference and in which:
FIG. 1 is a block diagram of a prior art printed circuit board production line;
FIG. 2 is a diagram of a printed circuit board production line in accordance with one embodiment of the present invention;
FIG. 3 is a diagram of a printed circuit board production line in accordance with another embodiment of the present invention;
FIG. 4 is a diagram of a printing system used in embodiments of the present invention;
FIG. 5 is a diagram of a dispensing system used in embodiments of the present invention;
FIGS. 6a-6d are diagrams depicting the operation of a shuttle conveyor system in accordance with one embodiment of the present invention;
FIGS. 7a-7h are diagrams depicting the operation of a shuttle conveyor system in accordance with another embodiment of the present invention; and
FIGS. 8a-8g are diagrams depicting the operation of the a shuttle conveyor system in accordance with another embodiment of the present invention.